Human beings perceive external information through five senses (sight, hearing, smell, taste, and touch), and more than 80 percent of it comes via the sense of sight. Therefore, the health of the vision is very important in order to maintain and improve the quality of life (QOL). Meanwhile, along with the aging of the population, there have been an increasing number of potential patients with eye diseases such as glaucoma, diabetic retinopathy, and age-related macular degeneration. This trend is assumed to further intensify. There is a need for early detection and prognostic control by screening to identify such potential patients to thereby maintain and improve QOL.
The screening of eye diseases is carried out with a variety of ophthalmic examination apparatuses. In particular, for patients with early disease before the subjective symptoms appear, an apparatus for understanding the eye's form and function is considered to be effective. Fundus cameras and scanning laser ophthalmoscopes (SLO) have been used as an apparatus of this kind. In recent years, an optical coherence tomography is used in addition to or in place of such a conventional apparatus.
The optical coherence tomography (OCT) provides a high-definition image (two-dimensional cross sectional image, three-dimensional image, enface image, etc.) of an ocular tissue (retina, choroid, lamina cribrosa, cornea, corner, etc.). By analyzing data obtained by the optical coherence tomography, the form (shape, thickness, area, volume, position, distribution, etc.) of a site of interest (tissue, lesion, etc.) can be obtained. Besides, there are technologies for determining the presence or risk of the eye disease by a comparison between the analysis data thus obtained and the database of normal eyes, and they have been put into practical use. Further, the optical coherence tomography is also used to measure the function such as the dynamics of blood and intraocular fluid.
In addition to being capable of acquiring the internal morphology of the eye tissue with high precision, the optical coherence tomography has various advantages in screening including, for example, that examination requires less time, the examination is performed without contact, and the examination can be performed even for an eye with a cataract or a small pupil. Further, the operability of the optical coherence tomography has been improved due to the automation of the alignment of its optical system with the eye, the automation (operation mode) of a series of actions for examination, or the like. Thus, even an unskilled person can easily conduct an examination.
It has been found that a sign of a disease other than eye diseases can be detected by ophthalmic examination. For example, there have been reports about the detection of early lesions of diseases such as diabetes, cancer, Alzheimer's disease, hypertension, arteriosclerosis, and the like. Generally, the screening of such diseases is performed by using an X-rays diagnostic apparatus, an X-ray CT apparatus, a positron emission tomography (PET) apparatus, a single photon emission computed tomography (SPECT) apparatus, a magnetic resonance imaging (MRI) apparatus, or the like. However, these modalities involve drawbacks such as radiation exposure, long examination time, and high costs. This makes it difficult to broadly offer the screening.
For example, Japanese Unexamined Patent Application Publication Nos. 2011-24930, 2013-248376, and 2015-35111 disclose the conventional technologies.